<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin:0;
            padding:0;
            line-height:12px
        }
    </style>
</head>
<body>
    <script src="./Js文件/index12.15.js"></script>
    <p id="demo">JavaScript 可以更改 HTML 内容。</p>
    <button type="button" onclick="document.getElementById('demo').innerHTML = 'Hello JavaScript!'">单击这里</button>
</body>
</html>